In the biomass field converting lignocellulosic biomass to ethanol is a common practice. If the biomass is a polysaccharide-containing biomass and it is lignocellulosic, a pre-treatment or soaking is often used to ensure that the structure of the lignocellulosic content is rendered more accessible to the enzymes, and at the same time the concentrations of harmful inhibitory by-products such as acetic acid, furfural and hydroxymethyl furfural are usually high and present problems in further processing.
In general terms the more severe the treatment, the more accessible are the cellulosic contents of the material. The severity of the steam explosion is known in the literature as Ro, and is a function of time and temperature expressed asRo=t×e[(T−100)/14.75]with temperature, T, expressed in Celsius and time, t, expressed in common units. The formula is also expressed as Ln (Ro), namelyLn(Ro)=Ln(t)+[(T−100)/14.75].
It is generally considered that a high Ro value is associated with a high number of unwanted by-products which inhibit the hydrolysis and fermentation of the biomass, such as furfural.
There exists therefore, the need to have a severe process with a high overall Ro which at the same time produces a product with low furfural and high sugar yields.